NEW YORK (Reuters) - An airplane entirely powered by the sun touched down in New York City late on Saturday, completing the final leg of an epic journey across the United States that began over two months ago.

The Solar Impulse, its four propellers driven by energy collected from 12,000 solar cells in its wings to charge batteries for night use, landed at John F. Kennedy Airport at 11:09 p.m. EDT, organizers said.

The experimental aircraft had left Dulles International Airport outside Washington for its last leg more than 18 hours earlier, on a route that took it north over Maryland, Delaware and New Jersey.

The spindly aircraft had been expected to land in the early hours of Sunday, but the project team decided to shorten the flight after an 8-foot (2.5 meter) tear appeared on the underside of the left wing.

The condition of the aircraft was declared sufficiently stable to continue, and pilot Andre Borschberg was not in danger, the organizers said.

The Solar Impulse is the first solar-powered plane capable of operating day and night to fly across the United States.

With the wingspan of a jumbo jet and the weight of a small car, the aircraft completed the first leg of the journey from San Francisco to Phoenix in early May and flew later that month from Phoenix to Dallas.

From there it flew to St. Louis, stopped briefly in Cincinnati, then flew on to Washington, where is has remained since June 16.

Intended to boost support for clean energy technologies, the project began in 2003 with a 10-year budget of $112 million (90 million euros).View gallery

Solar Impulse lands at JFK airport in New York July 6, 2013. REUTERS/Eric Thayer

It has involved engineers from Swiss escalator maker Schindler and research aid from Belgian chemicals group Solvay.

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ALMATY, Kazakhstan (Reuters) - A Russian rocket carrying three navigation satellites worth around $200 million crashed shortly after lift-off from the Russian-leased Baikonur launch facility in Kazakhstan on Tuesday after its engines suddenly switched off.

The accident led to a large spill of heptyl, a highly toxic rocket propellant, but there were no reports of casualties or of any immediate threat to nearby settlements.

State-run Rossiya-24 television showed footage of the Proton-M booster rocket veering off course seconds after take-off. It flew horizontally and began to come apart in flames, crashing in a ball of fire near the launch pad.

Russian Prime Minster Dmitry Medvedev, who has said that Russia has lost 10 satellites in seven failed launches in just over one year, ordered tighter controls put in place to avoid more embarrassing mishaps, his spokeswoman told Interfax.

The crash, which echoes the costly loss of three navigation satellites in 2010, will further damage the reputation of Russia's once-pioneering space program, cause delays in launches and threaten its hold on some 40 percent of the market for space launches.

Russia's space agency Roscosmos said the accident had been caused by the emergency switch-off of the rocket's engines 17 seconds into the flight. The shutdown could have been caused by a problem with the engine or the guidance system, the state-run RIA news agency reported.

Talgat Musabayev, head of Kazakhstan's space agency Kazcosmos, said nitric oxide - a product of burning heptyl - was much less toxic for humans. He said it was raining in the area, so toxic clouds would probably not reach the town of Baikonur some 60 km (38 miles) away.

However, the authorities instructed locals to stay at home and not to open windows, and ordered to close shops and public catering, said Kazakh Interior Minister Kalmukhambet Kasymov.

The estimated loss from the three satellites, meant for the trouble Glonass satellite navigation system, was about $200 million, Rossiya-24 reported.

Russia plans to spend more than 300 billion roubles ($9.1 billion) by 2020 on Glonass, its answer to the U.S. Global Positioning System (GPS) system.

The system, first conceived by the Soviet Union more than 40 years ago, has been plagued by failed launches, including one in 2010 in which three satellites were also lost, and by suspicions of corruption and embezzlement. Its chief designer was dismissed last year during a fraud investigation.

Russia's workhorse Proton rocket, known at the time under its UR-500 code, made its first test flights in the mid-1960s.

It was originally designed as an intercontinental ballistic missile to carry a nuclear warhead targeting the Soviet Union's Cold War foe the United States. But it was never deployed as a nuclear weapon.

Several crashes of Proton rockets accompanied by spills of heptyl have led to temporary strains in relations between Russia and Kazakhstan.

Russia is increasing spending on space and plans to send a probe to the moon in 2015, but the pioneering program that put the first man in space in 1961 has been plagued in recent years by setbacks, including botched satellite launches and a failed attempt to send a probe to a moon of Mars. ($1 = 32.9557 Russian roubles)

You might have heard that you can 3D print your own gun, but did you know that 3D printers can also churn out less-destructive objects, like a human liver or a prosthetic hand?

From dinosaur skeletons and plastic fetuses to sporting equipment and bikinis, 3D printing brings the miraculous, the useful and the flat-out bizarre to life.

Human body parts

You might not be able to sign up for a 3D-printed liver just yet, but scientists are already taking steps to make it possible in the near future.

Organovo, a San Diego-based startup specializing in the development of 3D-printed biological materials, prints functioning human liver tissue, and the company believes that it will one day be able to use this tissue to create an entire working organ.

And internal organs aren't the only body parts getting a boost from 3D-printing technology. Researchers at Cornell University recently used a 3D printer to create a human ear that could one day be implanted in a human being.

Prosthetics for people and pets

Who said prosthetics can't be pretty? Bespoke Innovations, a San Francisco-based company founded in 2009 by an orthopedic surgeon and an industrial designer, uses 3D printing to make custom-designed "fairings," or fashionable fitted covers for prosthetic legs.

Whether it's a tattoo graphic or chrome plating, Bespoke fairings add some flair to the otherwise monochrome world of prosthetic limbs.

And then there's Robohand, an Indiegogo-funded, open-source project developed by a South African man who lost four fingers in a woodworking accident and a mechanical-prop designer from Seattle.

Robohand is a 3D-printed prosthetic hand, a first-of-its-kind innovation that lets those without fingers grasp objects.

There are even 3D-printed prosthetics for pets. Take Buttercup, a duck born with a backward foot. Thanks to 3D-printing company NovaCopy, Buttercup now has two fully functioning feet and the chance to lead a normal, web-footed life.

Creating a 3D-printed foot is possible, but what about an entire 3D-printed dinosaur skeleton? Scientists at Drexel University in Philadelphia have developed a way to 3D print scaled-down prehistoric skeletons based on scans of real dinosaur bones.

Paleontologists hold together the miniaturized skeletons with artificial muscles and tendons, creating movable dinosaur robots. The scientists use these "robosaurs" to study the ways dinosaurs moved — research that would have been impossible using the life-size bones of an 80-ton dinosaur.

Marine biologists are also using 3D printing to study deepwater fishes, elusive animals that are difficult to observe in a lab. Replicas of dragonfish — a mysterious, deep-sea predator — can be 3D printed and studied in a lab without the need for high-pressure tanks or utter darkness.

Dead people

If you're going to 3D print extinct animals, you might as well print out a few dead people too, right?

That's what scientists at Loughborough University in the U.K. are doing. They've printed a full 3D replica of a man who has been dead since 1485: King Richard III.

And the British royal isn't the only one to be resurrected by 3D printing. Materialise, a 3D-manufacturing firm headquartered in Belgium, has created a full-scale 3D clone of King Tut, the young pharaoh who's been mummified since 1323 B.C.

If bones aren't really your thing, you might be interested to learn that 3D printers also may be able to whip out your next steak dinner.

Modern Meadow, a startup based in Columbia, Mo., is perfecting its methods for 3D printing edible meat products, as well as consumer-grade leather.

Using 3D bioprinting technology, the company aims to reduce the environmental costs associated with the raising, slaughtering and transporting of animals.

Snacks and fast food

Not a meat eater? Don't worry; there's a 3D-printed meal on the horizon for you, too. Researchers at NASA and Cornell University (among other institutions) are currently perfecting the art of 3D printing all kinds of food.

Sea scallops, cookies and banana-flavored gelatin are among the foods that have been successfully printed.

And then there's Marko Manriquez, a New York University graduate student who recently developed a 3D printer, dubbed the Burritobot, that assembles made-to-order burritos via a custom iPhone app.

Drug paraphernalia

Not in the mood for a 3D-printed burrito? Perhaps you would be if you had a 3D-printed bong. Thingiverse, MakerBot's digital community for sharing 3D designs, currently features dozens of files for DIY bongs, bubblers, hand grinders and dugouts —all standard tools of the smoker's trade.

And 3D-printed bongs aren't exclusively available for members of the maker community. Smokers can also buy a 3D-printed bong and other paraphernalia on Shapeways, a virtual 3D marketplace.

Sex toys

In case bongs aren't scandalous enough for you, here's a 3D-printed creation that will really get your blood flowing: the sex toy.

MakerLove, a website where 3D-printer owners can download their preferred erotic toy designs, is just one of many sites that demonstrate the free spirit of the 3D-printing industry.

Cars

A more traditional application for 3D printing is in automobile manufacturing. Many car and motorcycle makers use 3D printing — also called additive or digital manufacturing — to produce some of the finished parts they use in their cars.

And now 3D printers are being used to create an entire vehicle, the URBEE by Kor Ecologic. This futuristic-looking electric car was designed to use as little energy as possible and is capable of reaching more than 200 miles per gallon on the highway. The entire interior and exterior of the URBEE is 3D printed.

Drones

3D printing is taking to the skies as well. The University of Southampton in the U.K. is home to the first 3D-printed unmanned aerial vehicle (UAV), or drone.

The Southampton University Laser Sintered Aircraft (SULSA) can be assembled in 10 minutes once it's printed and doesn't require the use of any screws or traditional fasteners.

SULSA can fly on autopilot or via remote control for around 30 minutes and can reach speeds of 90 mph.

Houses

You might not have any need for a drone, but what about a 3D-printed house? Behrokh Khoshnevis, a professor at the University of Southern California, is currently working with NASA to design 3D-printed structures suitable for living on the moon, but his research also includes 3D-printed homes here on Earth.

In a recent TED talk, Khoshnevis explained the process of using a giant 3D printer, or a "contour crafting" machine that extrudes a concrete mixture to build a house layer by layer. Researchers believe this type of construction would be cheap and endlessly customizable.

Researchers at MIT also recently developed a superstrong 3D-printed material that replicates the fracture resistance of human bone and could one day be used to frame entire buildings.

One of the most widespread applications of additive manufacturing thus far has been in the fashion industry. Purses, cellphone cases and jewelry are all being 3D printed. But there are still a few wearable 3D-printed items that novelty seekers will love.

And what better accompanies a 3D-printed bikini than a 3D-printed pair of sunglasses? Make Eyewear sells some funky-looking frames that are printed to order.

For shoe lovers, there are plenty of 3D-printed options, including these beauties from Freedom of Creation designer Janne Kyttanen.

Human masks

A 3D printer can spit out more than just your outfit: With a little help from DNA sequencing, one Brooklyn, N.Y.-based artist is using a 3D printer to create eerily lifelike sculptures of human faces.

Heather Dewey-Hagborg, a Ph.D. student at Rensselaer Polytechnic Institute in Troy, N.Y., collects pieces of garbage like cigarette butts and chewing gum. She then extracts DNA samples from these bits of trash, sends the samples to be sequenced in a lab and enters the information she receives into a computer program that creates a 3D image of the anonymous DNA donor's face.

Japanese company Fasotec offers a similar product for expecting parents. Fasotec's 3D fetuses sell for over $1,000 and are meant to be used as desk ornaments.

Surfboards

One of the most widely acclaimed benefits of 3D-printing technology is its ability to execute custom-built designs more affordably than ever. Athletes could be the group that benefits the most from this highly tailored approach to manufacturing.

MADE, a Chicago-based startup, 3D prints "smart" windsurf, kite, surf and paddle boards. The boards are printed to the exact specifications of the user, with the help of microchips embedded in the user's ordinary surfboard.

These microchips collect information about how a person surfs and sends it to a corresponding smartphone app. The app aggregates this data, ultimately allowing a surfer to custom design a board based on his or her preferences and surfing behaviors —pretty gnarly stuff, dude.

Bacteria grown in a dish of fake urine in space behaves in ways never-before-seen in Earth microorganisms, scientists say.

A team of scientists sent samples of the bacteriumPseudomonas aeruginosa into orbit aboard NASA's space shuttle Atlantis to see how they grew in comparison to their Earth-dwelling counterparts.

The 3D communities of microorganisms (called biofilms) grown aboard the space shuttle had more live cells, were thicker and had more biomass than the bacterial colonies grown in normal gravity on Earth as controls. The space bacteria also grew in a "column-and-canopy" structure that has never been observed in bacterial colonies on Earth, according to NASA scientists. [The Human Body in Space: 6 Weird Facts]

"Biofilms were rampant on the Mir space station and continue to be a challenge on the [International Space Station], but we still don't really know what role gravity plays in their growth and development," NASA's study leader Cynthia Collins, an assistant professor in the department of chemical and biological engineering at Rensselaer Polytechnic Institute in Troy, N.Y., said in a statement. "Our study offers the first evidence that spaceflight affects community-level behaviors of bacteria, and highlights the importance of understanding how both harmful and beneficial human-microbe interactions may be altered during spaceflight."

Most biofilms found in the human body and in nature are harmless, but some are associated with disease, NASA officials said.

The space bacteria were cultured in artificial urine on NASA's Atlantis shuttle in 2010 and again in 2011 before the retirement of NASA's space shuttle program. Collins and her team of researchers used fabricated urine because it can be used to study the formation of biofilm outside and inside the body. Understanding how to safely remove and recycle waste is particularly relevant because of its importance in long-term spaceflight, NASA officials said.

"The unique appearance and structure of the P. aeruginosa biofilms formed in microgravity suggests that nature is capable of adapting to nonterrestrial environments in ways that deserve further studies, including studies exploring long-term growth and adaptation to a low-gravity environment," Collins said in a statement. "Before we start sending astronauts to Mars or embarking on other long-term spaceflight missions, we need to be as certain as possible that we have eliminated or significantly reduced the risk that biofilms pose to the human crew and their equipment."

Scientists sent 12 devices with eight vials of P. aeruginosa — a bacterium that can be associated with disease on Earth — into orbit on Atlantis. Once in space, astronauts on the shuttle introduced the bacterium to the fake urine while scientists on the ground began the control experiment.

After the samples arrived safely on Earth, Collins and her team took a detailed 3D image of the biofilms to investigate their internal structure, and used other research methods to investigate the colony's thickness and cell growth.

The study, published in the April 20 issue of the journal PLOS ONE, also could have implications for bacterial research on Earth. It's possible that this kind of research could help scientists and doctors more effectively limit the spread of infection in hospitals, Collins said.

England captain Alastair Cook has told his players to be ready for an almighty tussle when the Ashes series against Australia gets under way on Wednesday.

England are favourites to win their third Ashes in a row, a feat they have not achieved since 1956.

Ahead of the Trent Bridge Test, Cook said: "Australia have fantastic players and it will be one heck of a battle.

"Every Ashes series I have played in is always intense and that is what we have got to prepare ourselves for."

Cook, 28, who will be captaining his country in an Ashes series for the first time,added: "Cricket isn't played on paper and it never will be. It's about who delivers out there come tomorrow and the next 24 days of cricket."

The momentum in one of sport's oldest rivalries has shifted towards England in recent years following an era of Australian dominance.

Having lost eight straight series between 1989 and 2002-03, England have won three of the last four, culminating in a resounding 3-1 triumph in 2010-11, their first victory in Australia since 1986-87.

Cook said that victory had transformed his game and he is hoping similar success in this series can improve him further still.

"I think you are remembered for your Ashes performance. What happened in 2010-11 did change me as a cricketer, gave me a lot of confidence that I could perform at the highest level against a very good side under huge pressure. I probably hadn't achieved that in my career up to that point. I think it can change lives and careers and luckily I've managed to kick on from that moment and I see no reason why that can't continue."

He added: "In eight weeks' time, I'd love to be sitting at the Oval having won the Ashes. That's the ultimate aim as an English captain. You join a very elite band of cricketers who could say that. But we need to play well, withstand a lot of pressure, play with a lot of skill and win those crucial moments."England have had eight post-war Ashes-winning captains - Len Hutton, Peter May, Ray Illingworth, Mike Brearley, David Gower, Mike Gatting, Michael Vaughan, Andrew Strauss - and Cook hopes to join their ranks.

Recent form points to another England success, with Australia having suffered a 4-0 whitewash by India in March, three months afterEngland's 2-1 away victory over the same opposition.

The tourists have also endured a chaotic build-up to the series. Batsman David Warner was banned after punching England's Joe Root in a Birmingham bar and coach Mickey Arthur was replaced by Darren Lehmann just two weeks before the series.

Captain Michael Clarke, however, said Australia had put the turmoil behind them and, after encouraging performances in their warm-up matches against Somerset and Worcestershire, were capable of surpassing expectations.

"We come here as underdogs and we know it's going to be tough but I know the boys are up for the challenge," he said.

Ashes results i

"I think every single one of our boys has prepared as well as they possibly can. Now it's about going out on that stage and playing with freedom and backing your own ability.

"We have so much talent inside that room and I just want to see the guys play their natural games.

"We've spoken about a lot but I think the talking is done for us as a team now. Now it's not what you say, it's what you do."

While Clarke declared himself "100% fit" for the contest following a long-standing back problem, both captains vowed not to disclose their team selections until the toss at 10:30 BST.

Lehmann hinted last week that Warner could be a surprise inclusion at number six for Australia as the tourists look to unsettle England with an aggressive brand of cricket. Clarke said he was confident that Warner would be "a success" if selected.

England have won seven of their last nine Tests at Trent Bridge, including a famous victory in the 2005 Ashes, when unlikely batting heroes Matthew Hoggard and Ashley Giles helped put the hosts 2-1 up in the series with one to play.

The ground will be full to its 17,000 capacity for all five days of the match after tickets sold out within hours of going on sale in October.

Cook, who scored 766 runs at an average of 127.66 in the 2010-11 Ashes, said expectation levels across the country were consistent with his experiences in past contests against Australia.

"The biggest thing I've noted from playing in Ashes series is that when you've been successful, people come up to and tell you what a great series that was to watch," he said.

"Over the last couple of weeks, we've had a lot of people come up in the street and say good luck in the Ashes - that's very different to any other series.

The Ashes: En

"But you have to keep yourself very true to what you are and remember that it's another game of cricket.

"This is what we have been doing all our lives and we have handled these situations before so I don't see reason why we can't now."

Cook said: "It was an incredible moment for British sport when Andy Murray won Wimbledon and when the Lions won after such a long period of time. In our dressing room, there are a lot of big rugby and tennis fans, so watching that as a genuine British sports fan was fantastic.

"We'd love to be able to join them in that success but there's a hell of a lot of hard work to do first."

Veteran goalkeeper Mark Schwarzer has joined Chelsea on a one-year deal after leaving neighbours Fulham.

The 40-year-old was a free agent after turning down a new contract offer at Fulham.

He will provide competition to Czech keeper Petr Cech.

"It's a phenomenal club," said Schwarzer. "It's one of the biggest and best clubs in the world, and it's an honour to sign for Chelsea. I didn't take much convincing to come here."

Schwarzer is the first overseas player to make 500 English top-flight appearances.

The Sydney-born stopper moved to England in 1996, with Bradford City. He later joined Middlesbrough, for whom he made more than 400 appearances in 11 years, before switching to Fulham in 2008.

He is new Chelsea manager Jose Mourinho's third signing of the summer, following Dutch midfielder Marco van Ginkel, and Germany international forward Andre Schurrle to Stamford Bridge.

The FIA has banned media and 'non-essential personnel' from Grand Prix pit lanes after a cameraman was injured at last Sunday's German Grand Prix.

On Monday, F1 boss Bernie Ecclestone said that cameramen would only be allowed to film from the pit lane wall.

Other media will also be kept out of the pit lane, with the FIA saying in a statement: "Access for approved media will be confined to the pit wall."

Sunday's incident occurred as Red Bull driver Webber was leaving the pits following a tyre change that had taken longer than usual.

The Australian was released without the right rear wheel being properly secured and after it came free of the car it bounced into Allen, striking the Briton from behind.

The FIA also announced that it will seek an immediate change to regulations so that all team personnel working on cars during pit stops wear head protection, and that the speed limit in the pits is reduced from 100 kmh to 80 kmh.

The Tests will be followed by five ODIs and two T20s

KARACHI: Pakistan on Tuesday announced the schedule for its series against South Africa in October, involving two Tests, five one-day matches and two Twenty20 games.

The series will be played in Dubai, Abu Dhabi and Sharjah in the United Arab Emirates (UAE) -- Pakistan's de facto home grounds for international cricket since 2009.

Pakistan have been forced to play abroad because foreign teams have refused to tour the country since militants attacked the Sri Lankan cricket team in Lahore in 2009.

It will be South Africa's second series against Pakistan in the UAE, following two Tests, five one-dayers and two Twenty20s in 2010.

The Pakistan Cricket Board said the matches will be played between October 14 and November 15.

South Africa, ranked number one in Tests, will open the tour with a three-day warm-up match before the first Test in Abu Dhabi on October 14.

ISLAMABAD: Finance Minister Ishaq Dar on Tuesday said the government was committed to deal with tax evaders strictly in order to collect maximum revenue.

“In order to achieve the revenue target of Rs2.475 trillion for fiscal year 2013-14, we have to introduce new taxes, enhance tax base and stop tax evasion,” the finance minister said in an interview with a private TV channel here.

He said that agriculture sector contributes 23 per cent of total GDP, but overall tax collection from this sector is only Rs1 billion which is very low.

The agriculture tax law already exists, which is responsibility of the provinces. Therefore the provincial governments should enforce this law in order to enhance tax revenue from the sector, he added.

The budget, minister said envisages taxation measures which are estimated to yield Rs207 billion while another Rs300 billion would be mopped up through measures like IT connectivity, good governance, expansion of tax net, removal of SROs and plugging of leakages.

The FBR has been provided access to bank accounts, he remarked.

To ensure that this authority is not misused, the fine has been increased by ten times along with imprisonment to give comfort to parliamentarians and businessmen that this power would not be abused.

“Unfortunately as a result of this blast, 12 women, four children and one man have been killed and five children, one man and one woman have been wounded,” Herat province police spokesman Abdul Rauf Ahmadi told AFP.

KABUL: A bomb in western Afghanistan on Tuesday killed 12 women, four children and one man travelling in a three-wheel minivan, officials said, adding that at least seven other passengers were wounded.

“Unfortunately as a result of this blast, 12 women, four children and one man have been killed and five children, one man and one woman have been wounded,” Herat province police spokesman Abdul Rauf Ahmadi told AFP.

Sher Agha, the police chief of Herat's Obe district, said that the three-wheel vehicle struck a roadside mine planted by the Taliban as it travelled from Obe district centre to a nearby village.

Also on Tuesday, an Afghan soldier shot dead a Slovakian soldier, officials said, in the latest “insider attack” to shake efforts by the Nato coalition and the Afghan army to work together to defeat the Taliban insurgency.

The shooting occurred outside Kandahar airfield, one of the biggest military bases in southern Afghanistan and a hotbed of the 12-year conflict with the Islamist rebels, a senior Afghan officer told AFP.

Nato's International Security Assistance Force (Isaf) said in a statement that a “service member died when an individual wearing an Afghan National Security Force uniform fired his weapon at Isaf individuals”.

In line with Nato policy, the statement said the coalition would defer casualty identification procedures to the victim's national authorities.

Western officials in Kabul confirmed that the victim was Slovakian.

Eliot Spitzer’s improbable return to New York politics has all the elements of a Hollywood circus: hordes of television crews, crowds of curious onlookers and a high-wattage celebrity at the center, basking in the limelight.

Damon Winter/The New York Times

Eliot Spitzer, in Union Square on Monday, needs at least 3,750 signatures to make the ballot for New York City comptroller.

But for all the star power of his candidacy for city comptroller, Mr. Spitzer now faces the gritty and mundane realities of an 11th-hour campaign, as he must collect at least 3,750 valid signatures by the end of Thursday to qualify for the September primary. He faces a public ambivalent about his desire to return to government five years after scandal forced him from office. And his opponents, fellow Democrats as well as Republicans, say they plan to scrutinize every signature he collects, eager to block his candidacy on technical grounds.

The challenge became obvious within hours of Mr. Spitzer’s first campaign appearance on Monday, when he visited Union Square. After he departed, a small number of campaign workers, tired and complaining of sweltering heat, trolled the park in search of signatures to get Mr. Spitzer on the ballot. At the end of a few hours, many returned with pages of blank sheets.

In a radio interview on Tuesday, Mr. Spitzer said he recognized the hurdles. He said he hoped to collect 7,500 signatures — a cushion that he hopes will withstand scrutiny, but far fewer than the number of signatures being collected by other major candidates for city offices.

“The lawyer’s answer: Of course I’m concerned,” Mr. Spitzer said. “We have many, many people out in the streets gathering signatures and petitions, and I feel comfortable that we will get there.”

Mr. Spitzer’s spokeswoman, Lisa Linden, said that there were at least 100 campaign workers gathering signatures, a mix of volunteers and paid staff. Small teams of canvassers were seen in Union Square Park, and there were reports of campaign workers in the East Village and on the Upper East Side.

Still, there were signs of desperation. On Monday, the campaign posted an ad on Craigslist and other job sites, offering to pay canvassers $12 an hour, a standard rate. By Tuesday, the campaign was reportedly willing to pay $800 a day. On Wednesday night, the Spitzer campaign plans to hold a “petitioning party” at a Manhattan restaurant.

Manpower aside, Mr. Spitzer must also overcome byzantine rules that are a Tammany-style holdover from when the city’s power brokers were determined to limit ballot access.

As recently as 20 years ago, petitions required that signatories list their Assembly and election districts. An erroneous abbreviation or date could invalidate a name, or an entire sheet of names.

The process has been simplified recently — city charter revisions in 2010 reduced the number of signatures required and the amount of information voters must supply. Any registered Democrat who has not already signed a petition for a candidate for comptroller can sign Mr. Spitzer’s petitions. But some active Democrats are likely to be ineligible to do so because they have already signed omnibus petitions listing multiple candidates, including Mr. Stringer.

Most campaigns strive to collect at least three times the number of required signatures because errors frequently lead to the disqualification of signatures. The most common mistakes, said Martin Connor, an election lawyer who is not working on the comptroller’s race, include information that is altered without proper attribution, signature counts that are erroneous and incorrect dates.

“I think it’s a daunting task,” said Alan Handell, a senior vice president at Content Critical, who has printed petitions for many candidates for the last 40 years. “I think it’s hard to do 3,750 clean signatures in three days.”

The signatures must be submitted to the city’s Board of Elections, and can be challenged until Monday. The board would most likely adjudicate any disputed petitions by the end of July, election lawyers say.

During the last two days, Mr. Spitzer’s petition-gatherers have initiated conversations with questions unlikely to offend: Are you registered to vote? Are you a Democrat? Would you be interested in helping a fellow Democrat get on the ballot?

When it came time to mention Mr. Spitzer’s name, many of them said it as quickly as possible, or used only his first name.

Brian Bailey, 30, a camera loader, asked a canvasser about Mr. Spitzer’s background but was told only that he would push for higher corporate tax rates. Mr. Bailey offered his signature. Later, when informed by a reporter that Mr. Spitzer had resigned from office amid scandal, Mr. Bailey said he felt duped.

“I wouldn’t have signed if I had known that,” he said. “I don’t want someone with loose morals running our finances.”

When canvassers approached Rebecca Kelly, a preschool teacher who lives on the Upper East Side, she shooed them away. “No way, no way,” she said. “He’s a sleaze.”

Mr. Spitzer’s team delicately reminded Ms. Kelly that her signature did not mean she was voting for him, only that she believed he should be on the ballot. She was not persuaded. “He tarnished the reputation of New York and left us New Yorkers to the wind,” she said. “He’s untrustworthy.”

But every so often, the team was rewarded for its persistence.

Jerry Tucker, 76, who lives near Union Square and is the retired owner of a photo business, said he thought it was time to forgive Mr. Spitzer. “He had personal problems,” he said, “but that doesn’t change who he is deep down: a fighter.”